[clang] [Clang] Optimize -Wunsafe-buffer-usage. (PR #125492)

[Ilya Biryukov via cfe-commits]

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@@ -1948,31 +2294,59 @@ class DerefSimplePtrArithFixableGadget : public FixableGadget {
   const IntegerLiteral *Offset = nullptr;
 
 public:
-  DerefSimplePtrArithFixableGadget(const MatchFinder::MatchResult &Result)
+  DerefSimplePtrArithFixableGadget(const MatchResult &Result)
       : FixableGadget(Kind::DerefSimplePtrArithFixable),
-        BaseDeclRefExpr(
-            Result.Nodes.getNodeAs<DeclRefExpr>(BaseDeclRefExprTag)),
-        DerefOp(Result.Nodes.getNodeAs<UnaryOperator>(DerefOpTag)),
-        AddOp(Result.Nodes.getNodeAs<BinaryOperator>(AddOpTag)),
-        Offset(Result.Nodes.getNodeAs<IntegerLiteral>(OffsetTag)) {}
-
-  static Matcher matcher() {
-    // clang-format off
-    auto ThePtr = expr(hasPointerType(),
-                       ignoringImpCasts(declRefExpr(toSupportedVariable()).
-                                        bind(BaseDeclRefExprTag)));
-    auto PlusOverPtrAndInteger = expr(anyOf(
-          binaryOperator(hasOperatorName("+"), hasLHS(ThePtr),
-                         hasRHS(integerLiteral().bind(OffsetTag)))
-                         .bind(AddOpTag),
-          binaryOperator(hasOperatorName("+"), hasRHS(ThePtr),
-                         hasLHS(integerLiteral().bind(OffsetTag)))
-                         .bind(AddOpTag)));
-    return isInUnspecifiedLvalueContext(unaryOperator(
-        hasOperatorName("*"),
-        hasUnaryOperand(ignoringParens(PlusOverPtrAndInteger)))
-        .bind(DerefOpTag));
-    // clang-format on
+        BaseDeclRefExpr(Result.getNodeAs<DeclRefExpr>(BaseDeclRefExprTag)),
+        DerefOp(Result.getNodeAs<UnaryOperator>(DerefOpTag)),
+        AddOp(Result.getNodeAs<BinaryOperator>(AddOpTag)),
+        Offset(Result.getNodeAs<IntegerLiteral>(OffsetTag)) {}
+
+  static bool matches(const Stmt *S, llvm::SmallVector<MatchResult> &Results) {
+    bool Found = false;
+    auto IsPtr = [](const Expr *E, MatchResult &R) {
+      if (!E || !hasPointerType(*E))
+        return false;
+      const auto *DRE = dyn_cast<DeclRefExpr>(E->IgnoreImpCasts());
+      if (!DRE || !isSupportedVariable(*DRE))
+        return false;
+      R.addNode(BaseDeclRefExprTag, DynTypedNode::create(*DRE));
+      return true;
+    };
+    const auto PlusOverPtrAndInteger = [&IsPtr](const Expr *E, MatchResult &R) {
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ilya-biryukov wrote:

NIT: since it returns true, we should probably call it `IsPlusOverPtrAndInteger`

https://github.com/llvm/llvm-project/pull/125492